In an optical communication system, an optical module used for transmitting and receiving an optical signal is embedded. For example, a wavelength-tunable optical transmission device used in a backup system of a WDM (Wavelength Division Multiplex) network has been proposed (Patent Literature 1). In the wavelength-tunable optical transmission device, when a wavelength is changed, a controller changes a state of an optical gate from blocking to passing after the wavelength reaches a target value and becomes stable. In addition to this, a device with a built-in wavelength-tunable light source that blocks an optical output during wavelength change (Patent Literature 2), an integrated laser device (Patent Literature 3), and a wavelength-tunable optical output device (Patent Literature 4) have been proposed.
Meanwhile, for example, in the optical communication system in conformity with standards such as SFP (Small Form-Factor Pluggable) and XFP, use of the wavelength-tunable pluggable optical module has been developed. The wavelength-tunable pluggable optical module is an optical transceiver that is insertable into and removable from a socket of the optical communication device. When performing a control of the wavelength-tunable pluggable optical module, the wavelength-tunable pluggable optical module receives control information from the optical communication apparatus serving as a host side. Then, operation switching and changing of the wavelength-tunable pluggable optical module are performed according to the received control information.
In the wavelength-tunable pluggable optical module, there may be a case where the wavelength change is requested by the optical communication device. When complying with a request for the wavelength change, the wavelength-tunable pluggable optical module needs to autonomously perform and complete the change operation.